Using a localhost Callback URL and 401 Error

I was having problems with the 401 error and like many others followed the FAQ with no success.

The solution for me was to add the callback url in the twitter api setup as
http://127.0.0.1/PageName.aspx after which everything worked fine. I don't think it can be empty and still specify a callback URL which is used in the L2T authorization. After adding a URL in the api setup on dev.twitter it now redirects
to the submitted callback URL on CompleteAuthorization(Request.URI).

I'm posting this as I have yet to find the correct answer in any of the issues/discussions in the so it can help others out. It was driving me crazy.